The present invention relates to a power drive unit and a cargo compartment floor, in particular in cargo compartments of aircraft for loading and unloading of containers.
Aircraft used for the transport of cargo usually have cargo doors at a side of the aircraft. A loader moves a container into the aircraft through one of the cargo doors. In an area in the vicinity of the door inside the aircraft motorized devices in the floor of the cargo hold are able to pull the container all the way in and then direct it to the final storage and transportation location, where it will be locked in place. The container is moved forwards or backwards by motorized rollers in the floor, the so-called power drive units (PDUs).
Especially in the area near the doors the containers will have to be moved in different directions: First perpendicular to the main axis of the aircraft from outside to the inside, and then along the axis of the aircraft to move the container further into the cargo hold. Usually, ball mats—such as ones known from the document EP 1 527 993 A1—made from steel balls are employed in this area onto which the containers may be temporarily set down so that differently oriented PDUs may be raised and lowered sequentially for the different transportation modes.
Due to the heavy weight of ball mats their use in aviation is generally undesirable. One approach for reducing the weight of ball mats in the cargo hold of an aircraft is using ball mats made from lighter materials, such as disclosed in document DE 197 20 224 A1.
Other solutions try to dispose with the need of using ball mats. For example, document EP 0 355 251 A1 discloses a roller drive component with separate coaxially and adjoiningly arranged rollers that may be driven in opposite rotation in order to force a container supported on the roller drive component to turn sideways on the roller drive component.
However, there is still a need for solutions that enable a cargo hold to be equipped with lighter and simpler components.